Motor fuel



Patented Sept. 30, 1941 MOTOR FUEL John W. 'l'eter, Chicago, Ill, assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine No Drawing. Application August 1"], 1937, Serial No. 159,501

4 Claims.

This invention relates to anti-oxidants for gasoline and more particularly to the use of certain compounds for inhibiting the oxidation of gasolines. In its more specific aspect, the invention relates to theincorporation in cracked and polymer gasolines of a compound of the group consisting of 4-nitroso-2-methyl phenol, 4-nitroso-2-ethyl phenol and4-nitroso- 2, 5 dimethyl phenol.

Cracked gasolines and particularly polymer gasolines contain substantial quantities, of unsaturated compounds such as oleflns. It is well known that unsaturated compounds have a tendency to oxidize when the gasoline containing them is allowed to stand for an appreciable length of time after its production. There are two salient disadvantages which characterize the oxidation or deterioration of cracked and polymer gasolines originally containing substantial amounts of unsaturated compounds. Firstly,

' gum-like products are formed upon oxidation of these unsaturated comupounds. Such solid products may be 'formed while thegasoline is in storage tanks with the result that the gasoline has a cloudy appearance due to the precipitation of this solid matter. The gum-like product, together with additional solid matter formed in the gasoline tank of an automobile, for example,

tends to settle out in the gasoline lines and carburetor of the automobile engine. Secondly, the presence of the unsaturated compounds in the gasoline imparts to the gasoline a high antiknock rating which is higher in gasolines containing the larger quantity of these unsaturated compounds. However, when these unsaturated compounds are destroyed by oxidation the antiknock characteristic of the gasoline is seriously lowered.

For these two well recognized reasons there have been incorporated in cracked and polymer gasolines substances which have the property of efiectively inhibiting the oxidation of unsa rated compounds in the gasoline. Besides having this requisite inhibitory efiect it is also desirable that the gasoline anti-oxidants be substantially insoluble in water and highly soluble in the gasoline so that there will be no tendency for the anti-oxidant to be dissolved out of the gasoline during storage by any moisture in the gasoline.

I.have found that a compound of the group consisting of 4-nitroso-2-methyl phenol, 4-nitroso-2-ethyl phenol and 4-nitroso-2, 5 dimethyl phenol meet the several requirements of a highly desirable gasoline anti-oxidant. when small quantities of these nitrosated substituted phenolic compounds are incorporated in a gasolinev they exhibit a powerful inhibitory action with respect to oxidation of unsaturated compoimds contained in the gasoline, and have a low solubility in water with ready solubility in gasoline.

The effectiveness of the novel anti-oxidants of my invention will be apparent upon consideration of the following table showing the amount of inhibitor used and the length of the induction period for each anti-oxidant which was added in this amount to samples of a typical Mid-Continent cracked gasoline.

The efiicacy of the various anti-oxidants in the foregoing table was determined by the socalled olwgen bomb test on a cracked distillate as the standard gasoline. Samples of the untreated gasoline and of the'same gasoline in which all quantities of the various anti-oxidaigltsye li incorporated were tested for their to induction period. The oxygen bomb test in each case was carried out by placing a 200 c. 0. sample of the gasoline to be tested in a suitable container and then placing the container in a pressure bomb. After sweeping the atmosphere within the sealed bomb with oxygen, the bomb was filled with oxygen at a pressure of lbs. per square inch. The bomb was then placed in a steam bath, heated to 212 F., and maintained at this temperature throughout the test period. The maximum pressure within the bomb was recorded when the temperature thereof reached 212 F. The end of the induction period, that is the point at which the gasoline begins to oxidize, is indicated by a sharp and continued drop in the oxygen pressure within the bomb. By noting the time at which this maximum pressure was'obtained and the time at which the first appreciable drop in pressure occurred while the contents of the bomb were maintained at 212 R, an induction period was observed which comprises a direct measure of the relative tendency of the various gasoline apparent that the incorporation, for example, oi 0.003% by weight of 4-nitroso-2-ethyl phenol increases the induction period of a typical Mid- Continent cracked gasoline from 2.0 to 6.0 hrs., an increase of 4.0 hrs. The efiectiveness of this and the other gasoline anti-oxidants noted above, together with their ready solubility in gasoline, have the immediate result of markedly inhibiting the tendency for gasolines to oxidize and of dissolving in the gasoline without leaving an insoluble residue therein, without seriously affecting the color of the gasoline, and without imparting objectionable odor to the gasoline by the incorporation therein of these novel inhibitors.

The high efliciency of these novel anti-oxidants of my invention has the further salient advantage of lowering the cost index of the inhibitors below that of the inhibitors now in commercial use. The cost indices of 4-nitroso-2- methyl phenol as compared with two of the most successful commercial oxidation inhibitors now being used are shown in Table 11 together with the amount of each inhibitor which must be added to 1000 barrels (of 42 gallons) of a typical Mid-Continent gasoline to raise its induction period from 2.0 to 6.0 hours.

Table II Pounds of inhibitor/LOOO bbls. of gasoline to give 6' hrs. induction period Cost Inhibitor index Pounds CommercialA l Commercial-B 2. 4-nitroso 2-methyl phenol 3.

The cost index of each inhibitor recorded in Table II was obtained by dividing the cost per unit eificiency of any inhibitor by the cost per unit efliciency of commercial inhibitor A when each of the inhibitors was used in the same sample of gasoline in such a quantity as to produce a fuel of the same storage stability. The relative cost indices are compared by arbitrarily setting the cost index of commercial inhibitor A at 100. It should be noted in Table II that the cost index of 4-nitroso-2-methyl phenol is only 30 as compared with 100 and 84 for the two commercial inhibitors where a suflicient amount of each inhibitor is incorporated in the gasoline to impart to the gasoline an induction period of 6.0 hours where the untreated gasoline has an induction period of 2.0 hours. This low cost index is typical of the inhibitors of my invention and is cogent evidence of the advantages to be gained by the use of these inhibitors.

The anti-oxidants of my invention may be readily incorporated in cracked or polymer gasolines merely by the addition of the inhibitor to the gasoline. For example, a slurry of the antioxidant with some of the gasoline to be treated may be added to a stream of the gasoline as the latter is pumped into a storage tank. In such a case, the rate of addition of the slurry to the stream may be reduced with particular advantage to a rate substantially below that which will give a saturated solution of the anti-oxidant in the stream before the stream reaches the storage tank. Alternatively, the slurry 'may be introduced slowly into the low pressure side of a circulating pump associated with the gasoline storage tank, or may be incorporated in the gasoline at the same time, for example, that tetra-ethyllead is added to the gasoline. The inhibitors, on the other hand, may be incorporated in the gasoline with advantage by dissolving the inhibitor in a suitable solvent inert with respect to any eflect upon the gasoline or the inhibitor. These inert solvents may comprise aliphatic or cyclic alcohols such, for example, as methyl alcohol, ethyl alcohol, butyl alcohol, iso-propyl alcohol, or cyclohexanol. Thus, a concentrated solution of the inhibitor in an appropriate solvent may be prepared and added to the gasoline to be treated.

The quantities of the novel anti-oxidants of my invention which may be used with advantage should not be limited to the quantities used in the foregoing illustrations. The optimum amount of anti-oxidant which should be used in each case will vary with the characteristics of the gasoline to be treated and will be readily a-scertainable by simple tests on the gasoline by one skilled in the art. Furthermore, while each of the anti-oxidants referred to in the foregoing examples has been used alone, it should be noted that mixtures thereof may also be used with advantage.

I claim:

1. An improved motor fuel which comprises gasoline containing a small proportion of 4-nitroso-2-methyl phenol.

2. An improved motor fuel which comprises gasoline containing a small proportion of 4-nitroso-2-ethyl phenol.

3. An improved motor fuel which comprises gasoline containing a small proportion of 4-mitroso-2, 5 di-methyl phenol.

4. An improved motor fuel which comprises gasoline containing a small proportion of a compound of the group consisting of 4-nitroso-2- methyl phenol, 4-nitroso-2-ethyl phenol and 4-nitroso-2, 5 dimethyl phenol.

JOHN W. TETER. 

